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RE: How to optimize routing performance

To: Mårten Wikström <Marten.Wikstrom@xxxxxxxxxx>
Subject: RE: How to optimize routing performance
From: Martin Josefsson <gandalf@xxxxxxxxxxxxxx>
Date: Fri, 16 Mar 2001 09:08:06 +0100 (CET)
Cc: Rik van Riel <riel@xxxxxxxxxxxxxxxx>, "'linux-kernel@xxxxxxxxxxxxxxx'" <linux-kernel@xxxxxxxxxxxxxxx>, netdev@xxxxxxxxxxx
In-reply-to: <E6D22E487D45D411931B00508BCF93E75C0329@xxxxxxxxxxxxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx
On Fri, 16 Mar 2001, Mårten Wikström wrote:

[much text] 
> Thanks! I'll try that out. How can I tell if the driver supports
> CONFIG_NET_HW_FLOWCONTROL? I'm not sure, but I think the cards are
> tulip-based, can I then use Robert & Jamal's optimised drivers?
> It'll probably take some time before I can do further testing. (My employer
> thinks I've spent too much time on it already...).

I don't really know how to tell except
'grep CONFIG_NET_HW_FLOWCONTROL driverfiles'

You said that the cards where 100Mbit DEC cards, I assumed that by that
you meant that the cards use DECchip 21143 or similar chips.
If that's true you can use Robert & Jamal's optimised drivers.

Sorry to hear that your employer doesn't see the importance in such a test

> FYI, Linux had _much_ better delay variation characteristics than FreeBSD.
> Typically no packet was delayed more than 100usec, whereas FreeBSD had some
> packets delayed about 2-3 msec.

This sounds promising. So Linux had nice variations until it broke down
completely and stopped routing because of all the interrupts. I can almost
guarantee that with the optimised driver and CONFIG_NET_HW_FLOWCONTROL
you'll see a _big_ improvement in routingperformance.


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